In a study published in Environmental International and leaded by Nadia Vilahur PhD, researcher at CREAL, an ISGlobal research centre, in collaboration with Harvard University, the researchers measured in more than 180 placenta samples from the prospective cohort study INMA the Total Effective Xenoestrogenic Burden (TEXB-alpha), a biomarker evaluating the total estrogenicity due to exogenous lipophilic xenoestrogens found in placenta. The findings suggest that boys may be more susceptible to the effect of exposure to xenoestrogens during prenatal development, producing shifts in DNA methylation of certain sensitive genomic repetitive sequences in a tissue important for fetal growth and development.

Endocrine Disrupting Chemicals are molecules that are able to interact with the endocrine system of different species, including humans, leading to hormonal dysregulation and potentially be involved in the occurrence of diseases that are increasing in prevalence such as cancer, childhood obesity, fertility problems and neurobehavioral abnormalities. These chemicals are of special concern if exposure occurs during susceptible developmental windows to the effects of hormones like the prenatal period.

“We found that higher levels of placental TEXB-alpha exposure where associated with a significant 0.84% decrease in the methylation levels of an Alu element only in boys, while no effects were observed in girls”, explained Vilahur. Although statistically non-significant after multiple testing correction, a trend towards hypomethylation was also observed in two LINE elements also only in boys.

The results suggest that early xenoestrogen exposure may lead to sex-specific epigenomic deregulation in placenta so that males present increased vulnerability. “Studies on Endocrine Disrupting Chemicals should take into account sex as an important effect modifier in relation to early hormonal-related exposures”, concluded Vilahur.